refactor: comprehensive code quality improvements

[Luna161]

Summary

This PR delivers comprehensive code quality improvements across the entire Web-Calculator codebase: TypeScript source, HTML, CSS, and project configuration.

TypeScript Improvements

• Type safety: Renamed operation interface to PascalCase Operation, replaced any with proper constructor type new () => Operation, made second parameter optional to properly support unary operations
• Bug fixes: Added division-by-zero guards (division, modulo, wolfram), fixed backspace() to use Math.trunc for correct negative number handling, fixed decimal() comparison (<= → ===), reset this.op in clear(), reset lastResult in setZero()
• Logic fix: Unary operations (root2, power2, wolfram, flipNumber) no longer incorrectly set this.op, preventing wrong equal() behavior
• Cleanup: Removed all console.log debug statements, removed empty constructors, removed the redundant DOMContentLoaded click listener, replaced custom power() function with the ** operator, added missing semicolons

HTML Fixes

• Fixed double-quote typo in root2 onclick attribute
• Corrected stong-text typo → strong-text throughout
• Fixed all icon alt texts to match their operations (were all "÷")

CSS Improvements

• Merged duplicate #calculator and #numpad rule blocks
• Removed pointless border-radius on body
• Removed commented-out .column dead code
• Renamed .stong-text → .strong-text

Project Configuration

• Cleaned up tsconfig.json — removed 100+ lines of commented-out defaults
• Fixed package.json main field from non-existent myscripts.js → page/dist/script.js
• Added /page/dist/ to .gitignore — compiled output removed from source control

Commits

22 atomic commits with conventional commit messages (fix:, refactor:, style:, chore:).